Recently, there is a customer facility that includes a power generation apparatus (power generation device) and a power storage apparatus (electricity storage device). Regarding such a customer facility, there is provided a technique that enables a resident of the customer facility to act as an electricity retailer to sell the electricity to a person of another customer facility (see JP 2012-53721 A (hereinafter, referred to as “Document 1”), for example).
Document 1 mentions the feature of: estimating energy to be generated by a power generation device by calculation; and determining a power selling day based on a market price of power during a certain period, a price of power of an electric power company, and a price of power uniquely determined by the electricity retailer (the resident of the customer facility) so as to maximize the income. Document 1 also mentions a method of using a system power supply, the power generation device (power generation apparatus) and the electricity storage device (power storage apparatus) appropriately so as to maximize the income.
The technique described in Document 1 uses a photovoltaic power generation device and the electricity storage device, and the power generated by the photovoltaic power generation device is stored in the electricity storage device. In this technique, a day with a higher market price is determined as an optimum day for power selling, and the power stored in the electricity storage device is sold in this day.
In order to determine the optimum day for power selling, Document 1 also mentions the feature of: forecasting a price of power with regard to each of days in a certain period (N days); determining candidate dates for power selling in view of the prices of power; and determining a day(s) expected to be the highest, in a price of power, of the N days, based on past data. Document 1 also mentions that a day which is the highest, in a total of a price of power of the candidate date and a market price of power, of the N days is determined and is selected as the optimum day for power selling.
It is also mentioned in Document 1 that estimated total power consumption of the N days, an expected price of power of the power retailer, and a price of power of the system power supply are also used for the calculation of the income.
The technique described in Document 1 aims to maximize the income to be obtained from an electricity market, and for this purpose forecasts the market price of power with regard to each of multiple days, and determines a day expected to give the maximum income. According to the technique described in Document 1, therefore, the price of power with regard to each of the N days is needed to be forecasted by the resident of the customer facility.